code: def _create_data(self, length=1, image_channel=1, with_label=True):
      affine = np.eye(4)
      datalist = []
      for i in range(length):
          if image_channel == 1:
              image = np.random.randint(0, 2, size=(128, 128, 40))
          else:
              image = np.random.randint(
                  0, 2, size=(128, 128, 40, image_channel)
              )
          image_file = os.path.join(self.tempdir, f"image{i}.nii.gz")
          nib.save(
              nib.Nifti1Image(image.astype(float), affine), image_file
          )
  
          if with_label:
              # 3 slices has label
              label = np.zeros((128, 128, 40))
              label[0][1][0] = 1
              label[0][1][1] = 1
              label[0][0][2] = 1
              label[0][1][2] = 1
              label_file = os.path.join(
                  self.tempdir, f"label{i}.nii.gz"
              )
              nib.save(
                  nib.Nifti1Image(label.astype(float), affine),
                  label_file,
              )
              datalist.append(
                  {"image": image_file, "label": label_file}
              )
          else:
              datalist.append({"image": image_file})
  
      return datalist
  
file_path: MONAI/tests/test_deepgrow_dataset.py
imports: from __future__ import annotations
  import os
  import shutil
  import tempfile
  import unittest
  import nibabel
  import numpy
  from parameterized import parameterized
  from monai.apps.deepgrow.dataset import create_dataset
  from monai.utils import set_determinism
label_desc: Use image node_id 2 for calling the TestCreateDataset obj's underlying member method code with example usage: obj._create_data(length, image_channel, with_label) and returns: datalist